'''
画半圆,先转个方向
理解方向/坐标系
left(90)/right(90)
left(-90)/right(-90)
circle(100, 180)/circle(100, -180)/circle(-100, 180)
'''
from turtle import *

left(90) # right(90)
fillcolor('lightblue')
begin_fill()
circle(-100, 180)
end_fill()

done()
